Method for the preparation of pectin



ime on. as, 1945 f Herbert S. Bailey, Ontario, Calii., aasignor to California Fruit Growers Exchang e.LoaAngeleaCaiiL, a corporation of California Application February 21, 1945, Serial No. 579,140

comm.

- My invention relates to-a processlor extraction 01 pectin i'rom pectinous vegetable materials,

and particularly deals with a process iorreducing the viscosity of pectin solutions which are obtained. from such vegetable materials.

An object pf my invention isto provide a method for reducing the carbohydrate and other soluble-solids content of solutions obtained in processes for extracting pectin. from pectinous vegetable materials. I

Another object is to provide a method for alcoholic or other fermentation of the vegetable material to reduce the viscosity of the resultant pectin solution in order to provide for easier handling of said solution.

A further object is to provide a new and im- .proved process for extracting pectin from pectincontaining materials.

The drawing represents generally a flow sheet of the steps in a preierred embodiment of my new process.

1 Common processes for preparing a dried pectin or a pectin concentrate involve extraction of the soluble pectin from a vegetable material in which it occurs. This is generally accomplished by, as a that step, an aqueous treatment at somewhat elevated temperatures. Since the vegetable ma- 'terial ordinarily contains pectin largely as insoluble protopectin, the water usually contains an acid, for example suliurous, whose function is to hydrolize the protopectin and thus render it soluble in water. "There are many diflerent speciflc embodiments a: this process, varying as to the acid employed, time'and temperature of the aqueous treatment, amount oi water used,and in other details, but all of the most used proc- 'esses answerv to the above general description.

Apple pomace and-citrus fruit peel-are the most common sources of pectin-in commercial production, though others,. such as sugar-beets, may

. also be similarly treated.

Aiter'bbtaining in solution the pectin oi the sourcezmaterial, or at least a major portion of thesame, in order to proceed 'with preparation of a commercialproduct, it is obviously necesnot, be precipitated from solution, for example, by the use 01 alcohol, or in accordance with any of the several well known methods.

I have discovered a treatment involving a termentation stepto be interposed between the first treatment for obtaining the pectin in solution and the separation of the pectin solution from the residue. This treatment results in numerous advantages which will in part be enumerated herein and will in other part be obvious to those conversant with this art.

Generically, my process involves the alcoholic or other fermentation of the vegetable material after processing it to get the pectin dissolved in water, but before it is attempted to separate the spent vegetable residue from the pectin solution.

The .iollowing specific examples will disclose certain manners in which I have practiced my invention, but are not to be regarded as showing specifically all the waysin which my invention is capable of use.

' Example 1 One successful operation is as iollows:

Valencia oranges are burred and the peel ground to a coarse pulp, ashy passing the peel through a grinder with a lace-plate having about three-sixteenth inch holes. The batch consists of parts by weight as follows:

Parts Ground peel 1,300 Water 1,900 20 56. 3C h 7 Rm i 0.325

The batch is heated to 90 C. and held at that temperature for ten minutes. Then 11.6 parts 20 B. HCl are added and the mass held at about 90 C. for forty-five minutes. The batch is then cooled to about 40 C. and moculatedwith yeast, which has beencultured in orange juice. The inodillated'mass isstored at 37 C. until fermentation has progressed to the optimum point. The optimum is determined by tests of the viscosity of successively withdrawn samples 01 pectin. so I Iary to separate the solution from the large vol-v ume oi insoluble vegetable residue. This may be accomplished by pressing the material in a hydraulic press to squeeze out the pectin solution, and iiltering the solution to remove finely divided solids not retained in the press cake. Herealso commercial practice may vary, step is always necessary.

After clarification of the liquor, the pectin may. for the production 01' a dried prod but an equivalent I lution, when the viscosity has been reduced to the desired point, the fermentation is halted, and the mass heated and pressed to recover the pee: tin liquor. The pectin is precipitated with alcohol and dried. and subsequently tested for ash and Jelly grade. The grade in'a typical operation in accordance with thcsedetailcd directions. was and ash cdntent;3.2%. a

Example 2 i following description of another operation will give an indication variationsin practice.

may be used. as. for example, apples.

To one thousand pounds of wet, finely divided orange peel is added sumcient H61 to adjust the hydrogen ion activity to about pH 3.6 in order to prevent demethoxylation of pectin during the to 100 C. as by being passed through a device in the nature of an oil still heated by steam. From the still, the pulp is conveyed .to a tank where the hydrogen ion content of the pulp is at this pH and between 80 0. and as" c. for fortyfive minutes to convert protopectin to pectin and to dissolve the pectin into the aqueous phase.

The pulp is next vacuum cooled to approximately 35 C. and inoculated with a yeast oi the genus Saccharomyces. A small amount of KCl is generally used as a nutrient for the yeast. The inoculated pulp is then allowed to remain at between 33" C. and 35 C for a period of four to six 2,887,686 the specific examples as being suitable. other acids may be used as for example, sulfuric, nitric.

.heating step. The pulp is then heated quickly ,6

' adjusted to about pH 2.9. The pulp is maintained days for fermentation of carbohydrate materials.

The fermented pulp is again heated. this time to a temperature of about 88i C.. pressed in a batch type hydraulic press to recover the pectin liquor, and the liquor filtered- The filtered liquor is' concentrated in a vacuum pan and the pectin precipitated from the concentrated liquor bymeans of alcohol. The pectin is pressed, washed, and dried,asusual.

In considering further the alternative details of my process. as well, as the broader aspects 3 thereof the following may be pointed out with respect to'the various steps of the'process as idengified by the numerals appearing on the flow shee as well as organic acids like citric or tartaric If the pH of the source material is belowthe desired range it may be adjusted to within the range by use of suitable alkaline materials as sodium hydroxide or sodium carbonate, etc.

4. This step is directed to the solubilization of thepectous components and, as indicated on the flow sheet, may be carried out at a temperature of about 85 C. and at a pH of 2.9 for forty-five minutes although longer or shorter times may be desirable depending upon the temperature and pH of operation and also upon the kind and condition of the source materiaL- Also thisstep may, if desired, be combined with the preliminary heating step, indicated at 3, since the pH for converting the protopcctin and dissolving the pectin will ordinarily lie-within the range of 2.5 to 3.1, and this in. turn lies within the rangeof pH 2.5

to 3.6 suitable for the inactivation of enzymes.-

It becomes obvious, therefore, that under some operating conditions, steps 3 and 4 will merge into one. That is to say, the pH andtem-perature of the suspension will be adjusted to the proper range for obtaining pectin and during the course 1. While in the speciflm examples set forthy is to be ground or shredded or otherwise comminuted. This nduction in the particle size of the pectous source material should be carried to the point where the individual particles may be. reasonably quickly heated and cooled throughout theirentirety. Peel particles which have been of the conversion of the protcpectin to pectin the enzymes will be inactivated.

5. The. cooling of thepulp mass may be accom- 0 'plished in any suitable marinara: It is desirable that the mass be thoroughly cooled to within the range of from 30 C. tof C. prior to inoculation with the yeast. Under normal operating conditions and when suitable Equipment is available.

I prefer to cool the pulp' to at least about 33 C. and preferably around 30C. in order to prevent subsequent excessive breakdown of the pectin moleculeby heat.

' 6. Where I have referred to the use of yeast 40 for inoculation it is, ojfcourse, obvious that many yeasts are. capable bf fermenting sugars and other materials which are associated with the ground in a grinder having a face-plate containing holes with a diameter of from one-eighth to three-sixteenth of an inch will be satisfactory for my purposes. Too coarsepeelparticles should not be used. otherwise thorough heating in the subsequent steps will not be obtained. Peel which has been shredded as by being passed through a machine which cuts it lnto'strins about one-eighth inch thick is .very satisfactory for use in my process. 2. The amount of water used for suspending the pectous source material is not critical.

Enough water, should be used, depending upon the condition of the pulp. to give a handleabie suspension and one in which theyeast will have ready access to the pulp particles. Obviouslythe pulp suspension should be fluid enough to permit thorough stirring. The use of hot water will reduce the amount of heating required subscquently to reach the desired temperatures.

3. The acid may be added to the water in step.

12. m modification is advantageous in that a permits thorough intermixing of the acid in the indicated in 7 aqueous phas'e'of the system.

While hydrochloric acid has able pectin. reduced works rapidly and gives, contaminating micro-- organisms little chance to interfere. I have used -Mixtureseof different yeasts maybe used. ,My

- step immediately upon obtaining the pectin in pectous materialin. the various fruits and vegetables. That yeast is best which ferments the most of'such unwanted elements and which will operate under wide I conditions of temperature, hydrogen ion, etc. Ayeast is-desirable which many yeasts with successful, if variable, results.

invention is not dependent upon 'or iimitedto any particular-agent for obtaining the desired reduction of extraneous impurities ofthe pectin solution but its gist is the performance of this solution. Whatever agent is used,clearly-it must not substantially adversely affect the pectin. This is not to say that, for-example, no grade loss can be tolerated since a reasonable gradeloss may be more thanwcountered by gains in other respects such as increased yield of availcosts of filtration and concentration, etc. 1

While I have mentioned hereinbefore that suitable yeasts may becultured for my Process by means'of orange juice, it is. obvious that the v culturingmediumfor theyeastmay be any of the known media used for culturingyeast of the genus Saccharomyces. Furthermoraa portion of the. fruit or vegetable source material which is being used for the extraction of p ctin-may itself serve as a very satisfactory medium for culturing the 'yeasttobe-usedi 4 l 7. The time of fermentation is variable withseparation thereof growing yeast in said slurry thereby breaking down the non-pectouscarbohydrate substances in said slurry, and thereaiter separating a liquor containing water-soluble pectin from the slurry. i

6. A process for the preparation 01' pectin from pectous sourcemateriai comprising adjusting the pH of the material to within a range of 2.5 to 8.6,

heating. tire materialto a temperature or about 90- C. for a time to convert 'pectous eomponentsof said source material into watersoiuble pectin, cooling the slurry resulting from said treatment to between about 3010. and 40' 1 C. and prior to the separation thereof growing yeast in said slurry thereby breaking down the non-pectous carbohydrate substances in said sl urry, and thereafter separating a liquor eontaining water-soluble pectin from the slurry. v

HERBERT S. BAILEY. 

